A track for a tracked vehicle typically comprises an endless drive belt trained around drive sprockets or wheels for driving the belt in an endless path.
As illustrated in FIG. 1 (PRIOR ART), the belt 12 has an inner surface 14 and a ground-engaging surface 16, which, as it passes along a lower run of the belt 12, engages a surface (not shown) to be traversed.
The ground-engaging surface 16 comprises a series of projecting and transversally extending traction lugs 20. The traction lugs 20 are regularly spaced apart in the longitudinal direction of the track at a pitch P.
Typically, the endless belt 12 is made of flexible rubber and reinforcing rods 24 are embedded in the rubber material of the body of the belt 12, at the same pitch spacing P, each of which extends transversally substantially over the entire width of the track. The thickness of the track is locally increased in the region of the embedded reinforcing rods, corresponding to the region of the traction lugs 20. Such reinforcing rods 24 provide transverse rigidity to the track.
The inner track surface 14 is typically provided with a wheel-engaging portion that engages a drive wheel (not shown). In this example, the wheel-engaging portion comprises a series of drive lugs 18, which are spaced along the length of the inside surface of the belt 12 at the same pitch P, for engaging drive wheels (not shown) as is well known in the art. In this case, individual ones of the reinforcing rods 24 are located, along the track's longitudinal direction, where respective ones of the drive lugs 18 are located.
Ongoing efforts are made in the field of tracked vehicles to try and reduce the overall noise level of this type of vehicles. The regularity of the pitch spacing of the various elements discussed hereinabove has been recognized as contributing to the overall noise level of tracked vehicles.
Therefore, it has been contemplated achieving noise reduction through non-uniform spacing of the lugs forming the thread of the ground-engaging surface. It has also been suggested to ensure that the spacing of the external ground engaging lugs is at a different pitch from the spacing of the internal drive lugs (see for example U.S. Pat. No. 5,709,440, incorporated by reference as if fully set forth herein).
There is still a need in the art for noiseless rubber tracks.